Pipe used in chemical refining plants is often heated or cooled as a means of maintaining viscosity or preventing precipitation of materials conveyed. Means in the form of electrical resistance heating wires and cables for heating pipe, and tubes having heated or cooled mediums conveyed therethrough are commonly employed as a means of heating or cooling materials conveyed through the pipe.
It has heretofore been the practice to secure such heating or cooling means to the outer surface of pipe by a variety of methods. For example, heating or cooling means have been secured directly to the outer surface of the pipe by straps, clamps, heat conducting cement and the like. Such practices, however, do not generally provide a uniform means of pressing the heating or cooling means against the pipe and require the removal of the straps, clamps, and the like, from the pipe in order to repair or replace the heating or cooling means. A problem can arise in the case where it becomes difficult to remove a heating or cooling means that has been bonded to the outer surface of the pipe.
A variety of devices are disclosed in the prior art for securing heating or cooling means to the wall of a member to be heated or cooled. United States Patent 2,612,351, for example, discloses a device for mounting evaporation tubing on the wall of a refrigeration unit. The device comprises a C shaped channel secured to the wall of a unit. The channel has a strip of deformable heat conductive material disposed along its base against which the evaporator conduit is pressed. The conduit is held against the base by means of a cover plate that is shaped to the general contour of the conduit and has extensions which slidingly engage with flanges provided on the channel. Such a device, however, does not provide for resilient walls on the channel and requires a cover plate specially contoured for each type of conduit contained in the channel. The device would also be overly expensive for use on long lengths of pipe and would be difficult to utilize in that the cover plate is designed to slidingly engage with the channel which may not lend itself to practical use in many applications because of the particular piping configurations involved.
Another example of a heat apparatus is disclosed in U.S. Pat. No. 3,448,798 in which a U shaped groove is extruded in the wall of a member of containing a tube for use in heating or cooling the member. The groove has legs which can be bent over to contain the tube in the groove. Such apparatus does not however lend itself practically or economically to the problem of heating or cooling pipe already installed. Further, the cost and handling problems of pipe having such grooves extruded in their wall would be prohibitive in many piping installations. The ability to unbend and bend the groove legs repeatedly in order to replace or repair the tubes may also present a problem.
U.S. Pat. No. 3,398,262 discloses an electrical heater strip secured to a pipe by means of annular straps. Although such arrangements are sometimes used for the heating of pipe, the arrangement does not provide for pressing the heating strip in a uniform manner against the pipe and would require removing the annular straps in order to repair or replace the heater strip.
Another example of mounting tubes against the outer surface of pipe is disclosed in U.S. Pat. No. 3,844,345. Disclosed are a pair of control tubes contained in a crescent shaped encapsulation having a concave inner surface for mounting against the convex outer surface of production oil and gas tubing. The encapsulated control tubes are held against the pipe by means of straps. Although such an arrangement may be used to advantage for control purposes in well applications, it would be costly and impractical to replace or repair the control tubes because of their encasement in an elastomeric encapsulation and would further require the removal of the straps from the pipe in order to do so.
Another example of mounting electrical heating wires and conduit on pipe is disclosed in U.S. Pat. No. 3,971,416. Disclosed are both electrical conductors and cylindrical conduit (containing electrical wires) secured to a pipe. The electrical wire is covered by a heater housing and the conduit is bonded to the pipe by means of a heat transfer material. The heater housing may be welded to the pipe or, as the conduit, may be bonded to the pipe. Both are surrounded by an insulation layer having a protective outer cover. As hereinbefore described, both means disclosed would require removal of the bands or breaking of the welding in order to pull the wires from the end of a given section in order to replace or repair them. Further, the bands would not press the wires against the pipe in a uniform manner and the bonding may give rise to problems in the event it becomes difficult to remove the bonding material from the pipe.
An example of a C shaped clip having resilient outer portions for clinching a heat exchange conduit with a solar heat absorber is disclosed in U.S. Pat. No. 4,120,283. The clip has a central portion between the outer portion with an arch therein for supporting the conduit. The outer portions are designed to embrace and distort the heat absorber while holding the conduit and the central portion away from the heat absorber. The clip is designed so that it is necessary to remove the clip from the heat absorber in order to insert the conduit into or remove it from the clip.
Another example of the use of formable heat conductive material as a means of securing electrical heating wire or a tube to the outer surface of a pipe is disclosed in U.S. Pat. No. RE 29,332. Disclosed are a pair of electrical wires or a tube encased in a preshaped molding or extrusion of a heat transfer material. As in the case of U.S. Pat. No. 3,894,345 described above, the molding or extrusion has a concave surface along one side for conforming with the convex surface of the pipe. The molding or extrusion is covered by a channel member and the entire assembly is secured to the pipe by bands. As previously described for this type of an arrangement, it would be necessary to remove the bands in order to replace the wires or conduit and may be difficult or uneconomical to remove the conduit or wires from the preformed moldings or extrusion in order to effect their repair.
The referenced prior art does not provide a means of securing an elongated heating or cooling means to the outer surface of a pipe in such a manner that the heating or cooling means is uniformly pressed along its length against a flexible surface which in turn presses against and improves the heat transfer contacting relationship between the heating or cooling means and the pipe. Nor does the prior art provide for a means of securing a heating or cooling means against the outer surface of a pipe whereby the heating or cooling means may be easily mounted on or removed from the pipe for replacement or repair without the necessity of having to remove clamps, bands, bonded material, and the like. Nor does the prior art teach or suggest a means by which a heating or cooling means having a variety of cross-sectional shapes can be easily mounted on or removed from the outer surface of a pipe without having to loosen or remove the various clamps, bands, and the like heretofore known in the prior art.